The purpose of this study was to determine the mechanical efficiensy of rowing-ergometer exercise and to evaluate it from rowing motion analysis

Mohri, Yoshitsugu

Yamamoto, Hiroh

English

ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive

MECHANICAL EFFICIENCY OF ROWING FOR ELITE FEMALE ROWERS IN JAPAN '-'c~hi :Elli:U '!ohri ~":C·,:r2(Cr\· OZ 3iorne·::hcnics ?2(::.l:"t·, ~f Ecuc.,tion, Kanazal"a University <.;.n'=:2"'3, J2FaO, 92L' :-:!::-oh Y2~a:ilot0 ~~jor2(Or: oi 3iornechanics ::c~lcv oi ~duc5tion. ~2~azawa University ~anaza~a, ]a?a~, 920 .':':~.5T?-...1.CI ,­~~e ~CC?CSE oc this study was to determine the mechanical efficiensy of row­~~?E~~C~El=c ~xErcise and to evaluate it frcm rowing motion analysis. -:-·.,c~T" -=ignc junior female rowers (4-skilled championship crel" of Japan ::e.t~cn~l ?",~atta in 1984 and 24-unskilled ) served as subjects. The Evera5e age of subjects was 16.e±I.1 years (Mean±SD) and the mean values ef ~C, ~ax ~Ere 2.4±O.3 l/min and 42.1±3.7 ml/kg·min. Each subject was :ESt~~ thr=s~inutEs maximal sweep rowing at a competitive performance level :~ a ~cr,ut ~cwing Er;ometer. Work output was calculated by the flywheel ·:--='.'cl'..:t:'cns (r?") on the ergometer. Energy cost was ccmputed from total net :~~;~~ consu~D[ion. Exuired aas was collected by the open-circuit method_and iO~c-:":.'z~:: usin'? the ::cn'olander technique. The rowing motion was filmed by 1~"T. :jnt:cCITera 'J.'ith '-Sfps durin~ rowing erg-::m'Cter exercise. the films h~~S ~~alyz=d frame by framJor drive phase of strokes utilizing NAC -;--:,.tio~ 3.nalyzer '..Iith digitizer. Mechanical efficiency U'lEj of rO\,;ing i::G':"-:€i:f:!" exercisE ;."as 1l.4±O.4 % for the sl<illed and 1O.6±O.7 ~~ lor the '.r.£killE:':i. "lE of the skillecl was significantly higher than that' If the ,l::sk:llcd (p<'jJJ5). Based on the ratio of actual to possible sum of kne<: cr.G tr'.-'TlK an;ular velocity when the oar was perpendicular tn the sh,-·ll. -r:;,ti~n anal:lZE'i Er fie iency (MAE) was calcula ted wi th thp fonllllla of ,~elson ~t a:. (19~3i, II;1-.E of ro'"ing ergometer exercise was 89.4±3.8 % for the !k::':l;;d a~d 71) .6±10.9 % for the unskilled. 111\E of the skillcu was also !:~~i::ca~tlJ hi~her than that of the unskilled (p<0.05). These ~esu1ts 'J~~": s t",d tha t )~ 0 f s imu la ted rowing migh t be improved by the rou tine ~c£:l:'n'.; 'lnd that :'.1-.E 'dould be one of factors which influence on ME. There­,}~"" it is concluded that liE could be useful to assist the coach for unior ~e~al~ ro~eTS in establishing both training program and rowing echniqu~ of ~ach individual. 250 INTRODUCTION Competitive rOl,;ing performed over a distance of 2000m for men and lOOQn for wom~n with high-intensity exercise. Previous experience with exercise testing of rowers has shown that a high aerobic caracity in an impcrtat criterionfor international rowing success. However, rOlving performance is determined not only by aerobic capacity, muscular pOl,;er and training etc, and Iso influenced by skill to a great extent. As i~dex of rcwing skill, mechanical efficiency in rowing movement has been noted and measured in a basin or a rowing ergometer. In the previous studies of mechanical ef fici ncy, the measurmen t I,;ere almos t Ferformed for eli te male row rs but a few studies for female rowers. Moreover, fe\,; ~tudy has been discussed mechanical efficiency from a point of view in motion analysis for female rowers. Therefore. the purpose of this study was to detenrrire the mechanical efficiency of rowing ergometer exercise for junior female rowers and evaluate it from rowing motion analysis. MEIl-lODS Twenty eight junior female rowers (4-skilled championship crew of Japan National Regatta in 1984 and 24-unskilled)'",ere served as subjects. Japanese original r cing boats, namely Knukle four has mainly being used for female rowers. Therefore, they were rowers of Knukle four. Physical c~aracteristics of subjects were shown Table 1. Each subj cts \,;as tEsted thr~-minute maximal sweep rOlving at a competitive level on a Gamut ROI,;ing Er~ometer. \vork was calculated by following equation of Tsunoda et al.(1978). W=2·lf·r·g·N·M , where W~,;ork (joules)jTI=3.14, ratio of circl ; r=O. 184(~) radius of fly­wheel on r~ameter; g=9.8(N),acceleration of gr2vity; N=flywnee revolutions (q:m) after 3-min maximal LOwingjM=1.25(kg), work lord. Energy cost was calculated from total net oxygen consumption. Expired g s was collected by on-circuit method during following mini exercise of 0 to 1, 1 to 2, 2 to 3, and recovery of ° to 1, 1 to 2, 2 to 4, 4 to 8, 8 to 15, 15 to 30, 30 to 40 min. The last duration showed rest oxygen cOfolsumption as the baseline. G s volumes were measured using a dry gas meter and samples analyzed using the Scholander technique. Heart rate(HR) was recorded during the st 30 seconds of e ch gas collected duration by direct elec rocardiography. Kilocalorie equivalents were ca culated assuming equival nt of 5.05 K 1/1 O~ (based on an RQ of 1.00). Mechanical efficiency (ME) was determined with the formula (net efficiency=Work / Energy cost above at rest) 111 rowing motion was filmed by 16mmm cinecam r vlith 48fps during ro\,;ing ergometer exercise. THe camera was positioned at right angles to the pi in of moticn at a distance of ISm. A bord rn rked with a length of Im \,;as filmed in the location of the rower's body to determine the -conversion factor from film length to actual linear length. At least three complete 251 Table 1. MAE= V0 2Max (mllkg'minl V0 2Max ( lImin) Weight (I:::,) RElAT1VE KNEE ANGLE RELATIVE HIP ANGLE 162.8 61. 1 2.50 41. 45 2.5 1.4 0.26 2.39 162.5 57.5 2.43 42.10 {,.9 6.2 0.31 3.71 Height (cm) 16.3 0.9 Age (yrs) 900 Loo ,.­Unskilled(n-24) X SO Skilled(n£4) ;< 18.5 SO 0.9 Figure 1 Schematic of rower. (clted from the deta of Nelson et a1., 1983.) 252 possible sum of trunk and knee angular velocity if maximum angular velocity of trunk and knee occurr:,d when the oar was perpendicular to the shell. Physical characteristics for the skilled and unskilled rowers. strokes were filmea to allow the camera to reach th~ disired sp~ed during the last 30 seconds of each minute in exercise. The films were analvzed frame by frame for drive phase of strokes utilizing NAC motion analyzer with digitizer. The joint angles at the knee, hip and the inclination of the trunk I"ere defined according to the convention shown in figure J. Based on the ratio of actual to possible sum of ~£nee and trunk angular velocity when the oar was perpendicular to the shell, motion analyzed efficiency (~1AE) (,,'as calculated \"ith the follOl"ing equation of Nelson et a1. (J 983) actual sum of trunk and knee angular velocity when the oar was perpendicular to the shell. RESULTS AND DISCUSSION Changes of work of every 30 secc-ds during 3-min rowing ergometer exercise is shown Figure 2. Work of the skill was higher than that of the unskil ed. But changes of work indicated similar tendecies, that is, the first rapid "ncreases were caused by the start spurt and the fin 1 incre ses were caused by the 1 st spurt. Sum of I.ork was 23070.2t2571.9(j) for the skilled and 20456.S!2963.3(j) for the unskilled. Although work of the skilled was higher "than that of the unskilled, there was no statistical diffen:ence. Changes of HR and VOa during exercise and recovery on a rowing ergo­meter for the skilled and the unskilled are shd.,n in figure 3. HR increased to 174±io bpm for the skilled and 168tl I bpm for the un killed by the first minute, and chen increasd rapidly to 18StS bpm for the skilled and 18t8 bpm for the unskilled by the third minute. After rapid jncrease during the first minute of the rowing ergometer exercise, HR and V02 tended to level off at the near maximal aerobic capacity for both the skilled and the unskilled And then, gradually they decreasd to rest. Max HR in rowing exercise was approximately consistent with the previous reports. On the other hand, V0 1 of each minute in rowing exercise wa§ remarkably 10veE than che previous reports. Especially the values of peak VOL in this study vere about half as much as that of peak ~Ol for elite senior female rowers in USA. However, changes of HR and V02 in exercise showed similar tendencies to the prior studies. Work intensity of each minute in 3-maximal rowing was 6S.2t2.0 70 (the first min), 95.514.2 % (che second min), and 94.0 7.5 % (the third min) for the skilled respectivily, likewise 59.41:10.1 %, n'7±8.6 %, ;rt1d 9S.4f:6.6 % for the unskilled, respectivily. Work intensity at the only first min of the skilled was significancly higher than that of the unskilled (p<0.05). It appears that the skilled had more excellent cardiovascular response than the unskilled judging from work intensity of the firsc min. Total net energy cost was9.6±1.22 l/min for the skilled and 9.2±1.50 l/min for the unskilled. Although net energy cost of the skilled was higher than that of the~un~ skilled; there was no statistical differrence. Figure 4 shows mechanical efficiency (ME) and motion analvzed ef= fiency (MAE) of ergometric rowing for the skilled and unskilled. ME of the rmIing ergometer exercise vIas 11.4±0.4 % for the skilled and 10.6::t0.7 % for the unskilled, in the rage of 9.0 % to 12.0 % in all. Concerning the previous investigation, Henderson et al.(1925) found ME of the order of 20 Z~25 % on a rowing ergometer. Oi Ptampero et al.(1971) reported 10 %-20 % in the simulaced rowing in a basin and 18 %-23 % in actual rowing estimating from HR. Moreover, Tsunoda et al.(1977) (1978) (1979) reported 10 %-18 % in rowing ergometer exercise. Hagerman et al.(1978) (1979) also determined ME of simulated rowing and reported an average value of 14 % and the range of 16.07. to 17.5 %. In this way, it is considered that ME of simulated and accual rmllng ~n tne prev~ous c"epQrts 'das the rang," of ~;)Ol!t ;0 ;; co 25 ;L Although tfE in this study was ••1ithin the range of other prio;: repores. this result show5j the lowest value with the range of ~ffi among che others. 253 • • !,200 I 0 l,000-Ul 0 0 0~ 3800 :J 0 • 0•0 =3600 ~ •CL 3l,00 0 3: 3200, • 0: Skilled 3000 L .: Unskilled I , I 0 1 2 3 T I M E (mi n) figure 2. Work at 30 second intervals for a period of three minutes on the rowing ergometer for the skilled and unskilled. ,. ­~ 200 c ieO 0. ,SO D ~ jl,O ~ o 0• 0• O·Skilled • •Unsl<ill ed a: I 120 100 ,~ "'-0 0• ~ 0• 0• 0• 0 ';I 0 E 0 \j' <3 0 0 .:> 0 0 o 0 -- :t • I I I I 0 J 5 7 11 18 JJ l,J I 2.:erc:s2;::"- recovery ~ T:tv1E (min) Figure 3. HR and V02 during exercise and recovery on a rowing ergometer for the ~killed and the unskilled. 254 c ~ !.' \ \, \• ~\ I! [~ , \ : n. o ::<;:c::: o :~!r 255 o co <f1 ­w .­U ~ S~ w > T I M E FOR DRIVE PHASE (m 5) figure 5. Typical angular velocity of trunk, knee and hip as a function of time for the drive phased of the skilled. The vertical dotted line indicates when oar was perpendicular to the shell. Figure 4. ME and MAE of J-min rowing ergometer exercise for the skilled and the unskilled(* p<005) D Skilled 12 -- UnskilledT ~ 0 I 90 11 T ~ W 0 2: 80 w 10 <t 2: 70 REFERENCES 1) Oi Prampero, P.E., G, Cortile, F. Celentano, and p. Cerretelli.: Physiological aspects of rowing. J. Appl. 31: 853-857, 1971. 2, Gaesser, G. A. and G. M. Brooks.: Muscular efficiency during steady-rare exercise: ~ffect of speed and work rate. J. Appl. Physiol. 38: 1132-1 139, 1975.3) Ragerman, F.C. and W. D. Lee.:Measurement of oxygen consumption, heart rate, and '.lOrk output during rowing. Med. Sci. SpotLS.3: 155-160, 1971. 4) Hagerman, F.C., M.C. Connors, J.A. Gault, G.R. Hagerman. and W.J. Polinski· :Energy expenditure during simulated rowing. J. Appl. Physiol. 45:B7-93. 1978.5) Hagerman, F. C., P. G. Hagermao, and T. C. Micheison.: Physiological profiles of elite rowers. The Physician and Sportsmedicine. 7: 74-83,1979. 6) Henderson, Y. and H. W. Haggard.: The maximum of human power and its fuel. AM. J. Pljysiol. 72:264-282, 1925. 7) Lioyd, B.B. and R.M. Zachs.: THe mechanical efficiency of treadmill running agains t a horizotal imped ing force. J. Phys io 1. 223:: 355~363. \972. ~; :\,,~scn, "'.:'1: and C: J','hdule.: :<inematic analystS and '.!£fici~ncv ~5:!.~ate Jr lntercolle!!l.ste female rowers. ~1ed. Sci. Sports Exerc. 15: j35-j41. 1983 ~ r5~noda ~t al.: The :irsr ,eports, boat. Report of research center in ;:>hvsical ;,ducation. 31-43. 1977. 10' T~notia et al.: The second reports, boat. Rep. Res. Cent. Phys. ;49-68, 1978. 1\) Tsunoaa 2t al.: Relationship vi energy expenditure in 6-win rowing. Rep. Res. Cent. Phys. Ed.: 107-111,1979. 12' Jhipp 3. J., C. Seard and K. Wasserman.: Oxygen deficit-oxygen debt :elac onships and e£ficie~cy of anaerobic work. J. Appl. Physiol. 2B: 452""':' 6, 1970. 256 

MECHANICAL EFFICIENCY OF ROWING FOR ELITE FEMALE ROWERS IN JAPAN

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MECHANICAL EFFICIENCY OF ROWING FOR ELITE FEMALE ROWERS IN JAPAN

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